Two 1-ohm subs can easily be wired in series for a 2-ohm load.

if an amp is designed to be 1 ohm stable, then its ok. running an amp not designed to do it can/will end up bad. there are some amps that can do .

so 1 ohm is just fine. as long as you stay in the range that the manufacturer specifies you are good. In order for a given amplifier to operate into a 1 ohm load, you pay more for the same amount of power than if you were operating at 4 ohms.

So if wiring two Single 4 Ohm subs you would take 4 Ohm and divide it by the number of voice coils. So 4 Ohm divided by two voice coils will equal a 2 Ohm load. Okay now as you saw above the single 4 Ohm subs wired in a parallel resulted in a 2 Ohm load, just what we needed for the amplifier example from above.

A parallel wiring turns those 2 8 ohm speakers into a system of 4 ohms total. A parallel wiring of 4 16 ohm speakers has a system of 4 ohms total as well. To simplify parallel wiring, pretend your speaker system has a total of 2 speakers with 16 ohms each.

The lower the impedance, the more efficiently it allows the electric signal, which is basically the music, to pass through the speaker. Most speakers are rated at 4, 6 or 8 ohms, and cheaper receivers can sometime have issues driving low-impedance (namely 4 ohm) speakers.

You can wire 20 subs to a monoblock amp if you wire them correctly. Just divide the power into the two subs. So if your amp is a 500 watt amp, each sub would get 250. You can theoretically connect as many speakers as you want to a monoblock amp.

1 ohm or two ohm makes absolutely no difference, it simply depends on what load the amplifier was designed for, what the amp circuits were optimized for. Everything else being equal, an amp built for and running in 1 – ohm will behave exactly the same as an amp designed for and running in 2 – ohms.